U.S. patent number 9,947,729 [Application Number 15/058,323] was granted by the patent office on 2018-04-17 for organic electroluminescent element, lighting device, and lighting system.
This patent grant is currently assigned to Kabushiki Kaisha Toshiba. The grantee listed for this patent is Kabushiki Kaisha Toshiba. Invention is credited to Akio Amano, Daimotsu Kato, Tomio Ono, Tomoko Sugizaki.
United States Patent |
9,947,729 |
Amano , et al. |
April 17, 2018 |
Organic electroluminescent element, lighting device, and lighting
system
Abstract
According to one embodiment, an organic electroluminescent
element includes a substrate, a first electrode, a second
electrode, an organic layer and a first conductive unit. The
substrate is light-transmissive. The second electrode is provided
between the substrate and the first electrode. The second electrode
is light-transmissive. The second electrode includes a first region
and a second region. A direction connecting the first region and
the second region intersects a first direction connecting the
substrate and the first electrode. The organic layer is provided
between the second electrode and the first electrode. The first
conductive unit is provided between the first region and a portion
of the substrate. The first conductive unit is electrically
connected with the second electrode. The first conductive unit
includes a third region and a fourth region. A portion of the
fourth region is disposed between the substrate and at least a
portion of the third region.
Inventors: |
Amano; Akio (Machida,
JP), Sugizaki; Tomoko (Kawasaki, JP), Kato;
Daimotsu (Kawasaki, JP), Ono; Tomio (Yokohama,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Kabushiki Kaisha Toshiba |
Minato-ku |
N/A |
JP |
|
|
Assignee: |
Kabushiki Kaisha Toshiba
(Minato-ku, JP)
|
Family
ID: |
56845392 |
Appl.
No.: |
15/058,323 |
Filed: |
March 2, 2016 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
|
US 20160260784 A1 |
Sep 8, 2016 |
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Foreign Application Priority Data
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Mar 5, 2015 [JP] |
|
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2015-043427 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
51/5275 (20130101); H01L 51/5221 (20130101); H01L
27/3225 (20130101); H01L 51/0037 (20130101); H01L
51/5212 (20130101); H01L 51/5218 (20130101); H01L
27/3244 (20130101); H01L 2251/558 (20130101) |
Current International
Class: |
H01L
27/32 (20060101); H01L 51/52 (20060101); H01L
51/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2007-200788 |
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Aug 2007 |
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JP |
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2008-103305 |
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May 2008 |
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JP |
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2010-251401 |
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Nov 2010 |
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JP |
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2011-108637 |
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Jun 2011 |
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JP |
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2012-49112 |
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Mar 2012 |
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JP |
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2012-94348 |
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May 2012 |
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JP |
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2014-150030 |
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Aug 2014 |
|
JP |
|
Primary Examiner: Wilson; Allan R
Attorney, Agent or Firm: Oblon, McClelland, Maier &
Neustadt, L.L.P.
Claims
What is claimed is:
1. An organic electroluminescent element, comprising: a substrate
being light-transmissive; a first electrode; a second electrode
provided between the substrate and the first electrode, the second
electrode being light-transmissive and including a first region and
a second region, a direction connecting the first region and the
second region intersecting a first direction connecting the
substrate and the first electrode; an organic layer provided
between the second electrode and the first electrode; a first
conductive unit provided between the first region and a portion of
the substrate and electrically connected with the second electrode,
the first conductive unit including a third region and a fourth
region, a portion of the fourth region being disposed between the
substrate and at least a portion of the third region; and a first
insulating layer including a fifth region provided between the
third region and the second region in a second direction
intersecting the first direction, one other portion of the fourth
region not overlapping the fifth region in the first direction, and
the one other portion of the fourth region contacting the second
electrode.
2. The element according to claim 1, wherein the first insulating
layer further includes a sixth region provided between the first
conductive unit and the first region.
3. The element according to claim 1, further comprising: a second
conductive unit; and a second insulating layer, the second
electrode further including a seventh region and an eighth region,
a direction connecting the first region and the seventh region
being aligned with the second direction, a direction connecting the
second region and the eighth region being aligned with the second
direction, the second conductive unit being provided between the
seventh region and one other portion of the substrate and
electrically connected with the second electrode, the second
conductive unit including a ninth region and a tenth region, a
portion of the tenth region being disposed between the substrate
and at least a portion of the ninth region, the second insulating
layer including an eleventh region provided between the ninth
region and the eighth region in the second direction.
4. The element according to claim 3, wherein the second insulating
layer further includes a twelfth region provided between the second
conductive unit and the seventh region.
5. The element according to claim 3, wherein the substrate contacts
the second electrode between the first conductive unit and the
second conductive unit.
6. The element according to claim 1, wherein a thickness along the
first direction of the third region is thicker than a thickness
along the first direction of the fourth region.
7. The element according to claim 1, wherein the first conductive
unit further includes a side surface intersecting the first
direction.
8. The element according to claim 7, wherein the first conductive
unit includes at least one element selected from the group
consisting of Mo, Ta, Nb, Al, Ni, and Ti.
9. The element according to claim 1, wherein the third region
further includes a first side surface aligned with the first
direction, and the fourth region further includes a second side
surface aligned with the first direction and separated from the
first side surface in the second direction.
10. The element according to claim 9, wherein the fourth region
further includes a first portion, and a second portion arranged
with the first portion in the second direction, and one other
portion of the third region is provided between the first portion
and the second portion in the second direction and contacts the
substrate.
11. The element according to claim 9, wherein a light transmittance
of the fourth region is higher than a light transmittance of the
third region.
12. The element according to claim 9, wherein the third region
includes at least one element selected from the group consisting of
Mo, Ta, Nb, Al, Ni, and Ti, and the fourth region includes an oxide
including at least one element selected from the group consisting
of In, Sn, Zn, and Ti.
13. The element according to claim 1, wherein a light reflectance
of the first electrode is higher than a light reflectance of the
second electrode.
14. The element according to claim 1, wherein a refractive index of
the second electrode is higher than a refractive index of the
substrate and lower than a refractive index of the organic
layer.
15. The element according to claim 14, wherein the refractive index
of the second electrode is 1.6 or less.
16. The element according to claim 1, wherein the second electrode
includes polyethylene dioxythiophene.
17. The element according to claim 1, wherein the first insulating
layer includes one of silicon oxide, silicon nitride, or silicon
oxynitride.
18. An organic electroluminescent element, comprising: a substrate
being light-transmissive; a first electrode; a second electrode
provided between the substrate and the first electrode, the second
electrode being light-transmissive and including a first region and
a second region, a direction connecting the first region and the
second region intersecting a first direction connecting the
substrate and the first electrode; an organic layer provided
between the second electrode and the first electrode; a first
conductive unit provided between the first region and a portion of
the substrate and electrically connected with the second electrode,
the first conductive unit including a third region and a fourth
region, a portion of the fourth region being disposed between the
substrate and at least a portion of the third region; an other
portion of the fourth region contacting the second electrode;
wherein a cross-sectional shape of the first conductive unit is a
trapezoid, and wherein the first conductive unit contacts the
second electrode at lower portion of the trapezoid.
19. An organic electroluminescent element, comprising: a substrate
being light-transmissive; a first electrode; a second electrode
provided between the substrate and the first electrode, the second
electrode being light-transmissive and including a first region and
a second region, a direction connecting the first region and the
second region intersecting a first direction connecting the
substrate and the first electrode; an organic layer provided
between the second electrode and the first electrode; a first
conductive unit provided between the first region and a portion of
the substrate and electrically connected with the second electrode,
the first conductive unit including a third region and a fourth
region, a portion of the fourth region being disposed between the
substrate and at least a portion of the third region; an other
portion of the fourth region contacting the second electrode;
wherein a cross-sectional shape of the first conductive unit is a
trapezoid, and wherein the first conductive unit contacts the
second electrode at lower portion of the trapezoid wherein a length
of the third region in a direction crossing the first direction is
shorter than a length of the fourth region in the direction
crossing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority
from Japanese Patent Application No. 2015-043427, filed on Mar. 5,
2015; the entire contents of which are incorporated herein by
reference.
FIELD
Embodiments described herein relate generally to an organic
electroluminescent element, a lighting device and a lighting
system.
BACKGROUND
In recent years, organic electroluminescent elements in
applications such as planar light sources, etc., are drawing
attention. It is expected that applications that could not be
realized by conventional lighting appliances and light sources will
be realized by an organic electroluminescent element due to the
features of being thin, lightweight, and having planar light
emission. In the organic electroluminescent element, an organic
light emitting layer is provided between a first electrode (an
anode) and a second electrode (a cathode). Light is emitted from
the organic light emitting layer by applying a voltage between
these electrodes. There is a lighting device in which the organic
electroluminescent element is used as the light source. There is a
lighting system that includes multiple organic electroluminescent
elements and a controller that controls the multiple organic
electroluminescent elements. It is desirable for the organic
electroluminescent element to have a greater surface area.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view showing an organic
electroluminescent element according to a first embodiment;
FIG. 2 is a schematic cross-sectional view showing a portion of the
organic electroluminescent element according to the first
embodiment;
FIG. 3 is a schematic cross-sectional view showing an organic
electroluminescent element according to a second embodiment;
FIG. 4A and FIG. 4B are schematic perspective plan views showing
the organic electroluminescent element according to the second
embodiment;
FIG. 5 is a schematic cross-sectional view showing a portion of an
organic electroluminescent element according to a third
embodiment;
FIG. 6 is a schematic cross-sectional view showing a lighting
device according to a fourth embodiment; and
FIG. 7A and FIG. 7B are schematic views showing lighting systems
according to a fifth embodiment.
DETAILED DESCRIPTION
According to one embodiment, an organic electroluminescent element
includes a substrate, a first electrode, a second electrode, an
organic layer and a first conductive unit. The substrate is
light-transmissive. The second electrode is provided between the
substrate and the first electrode. The second electrode is
light-transmissive. The second electrode includes a first region
and a second region. A direction connecting the first region and
the second region intersects a first direction connecting the
substrate and the first electrode. The organic layer is provided
between the second electrode and the first electrode. The first
conductive unit is provided between the first region and a portion
of the substrate. The first conductive unit is electrically
connected with the second electrode. The first conductive unit
includes a third region and a fourth region. A portion of the
fourth region is disposed between the substrate and at least a
portion of the third region.
According to one embodiment, a lighting device includes an organic
electroluminescent element and a power supply unit. The organic
electroluminescent element includes a substrate, a first electrode,
a second electrode, an organic layer and a first conductive unit.
The substrate is light-transmissive. The second electrode is
provided between the substrate and the first electrode. The second
electrode is light-transmissive. The second electrode includes a
first region and a second region. A direction connecting the first
region and the second region intersects a first direction
connecting the substrate and the first electrode. The organic layer
is provided between the second electrode and the first electrode.
The first conductive unit is provided between the first region and
a portion of the substrate. The first conductive unit is
electrically connected with the second electrode. The first
conductive unit includes a third region and a fourth region. A
portion of the fourth region is disposed between the substrate and
at least a portion of the third region. The power supply unit is
electrically connected with the first electrode and the second
electrode. The power supply unit supplies a current to the organic
electroluminescent element.
According to one embodiment, a lighting system includes a plurality
of organic electroluminescent elements and a controller. Each of
the organic electroluminescent elements includes a substrate, a
first electrode, a second electrode, an organic layer and a first
conductive unit. The substrate is light-transmissive. The second
electrode is provided between the substrate and the first
electrode. The second electrode is light-transmissive. The second
electrode includes a first region and a second region. A direction
connecting the first region and the second region intersects a
first direction connecting the substrate and the first electrode.
The organic layer is provided between the second electrode and the
first electrode. The first conductive unit is provided between the
first region and a portion of the substrate. The first conductive
unit is electrically connected with the second electrode. The first
conductive unit includes a third region and a fourth region. A
portion of the fourth region is disposed between the substrate and
at least a portion of the third region. The controller is
electrically connected with one of the plurality of organic
electroluminescent elements. The controller controls an intensity
of a light emission of the one of the plurality of organic
electroluminescent elements.
Various embodiments of the invention will be described hereinafter
with reference to the accompanying drawings.
The drawings are schematic or conceptual; and the relationships
between the thicknesses and widths of portions, the proportions of
sizes between portions, etc., are not necessarily the same as the
actual values thereof. The dimensions and/or the proportions may be
illustrated differently between the drawings, even in the case
where the same portion is illustrated.
In the drawings and the specification of the application,
components similar to those described in regard to a drawing
thereinabove are marked with like reference numerals, and a
detailed description is omitted as appropriate.
First Embodiment
FIG. 1 is a schematic cross-sectional view showing an organic
electroluminescent element according to a first embodiment.
The organic electroluminescent element 110 according to the
embodiment includes a first electrode 10, a second electrode 20, an
organic layer (an organic light emitting layer) 30, a substrate 40,
a first conductive unit 51, a second conductive unit 52, and a
first insulating layer 60.
The substrate 40 is, for example, light-transmissive. The substrate
40 is, for example, a transparent substrate. The substrate 40
includes, for example, an inorganic material such as alkali-free
glass, quartz glass, etc. The substrate 40 may include a plastic
such as polyethylene, polyethylene terephthalate (PET),
polyethylene naphthalate (PEN), polyimide, polyamide,
polyamide-imide, a liquid crystal polymer, a cycloolefin polymer,
etc. The substrate 40 may include a polymer film, etc. The
substrate 40 is, for example, a glass substrate. It is favorable to
use a transparent material to extract the light emission. The
configuration, structure, size, etc., of the substrate 40 are
appropriately selected according to the application, the purpose,
etc.
Here, a direction perpendicular to the substrate 40 is taken as a
Z-axis direction. One direction parallel to the substrate 40 is
taken as an X-axis direction. One direction perpendicular to the
X-axis direction and the Z-axis direction is taken as a Y-axis
direction. The X-axis direction and the Y-axis direction are
parallel to the substrate 40. The X-axis direction and the Y-axis
direction are perpendicular to the Z-axis direction. The Z-axis
direction corresponds to the thickness direction of the substrate
40.
The first electrode 10 is, for example, light-reflective. The first
electrode 10 functions as a cathode. The light reflectance of the
first electrode 10 is higher than the light reflectance of the
second electrode 20. The first electrode 10 is separated from the
second electrode 20 in the first direction. In the embodiment, the
first direction is the direction from the substrate 40 toward the
first electrode 10. The first direction is, for example, the Z-axis
direction. The second direction is, for example, the X-axis
direction.
The first electrode 10 includes, for example, at least one of
aluminum or silver. For example, the first electrode 10 includes an
aluminum film. An alloy of silver and magnesium may be used as the
first electrode 10. Calcium may be added to the alloy. The first
electrode 10 is not limited to these materials. For example, the
first electrode 10 is provided in a fine wire configuration or a
lattice configuration that cannot be visually confirmed. For
example, the fine wire configuration or the lattice configuration
that cannot be visually confirmed is provided with a line width and
a spacing of about 100 micrometers (.mu.m)/100 .mu.m or about 100
.mu.m/500 .mu.m. For example, the pattern configuration of the
first electrode 10 may be a comb-like configuration.
The second electrode 20 is, for example, light-transmissive. The
second electrode 20 functions as an anode. The second electrode 20
is, for example, a transparent electrode. The second electrode 20
is provided between the substrate 40 and the first electrode 10.
The light extraction efficiency can be increased by using a low
refractive index material as the transparent electrode. The second
electrode 20 includes, for example, polyethylene dioxythiophene
(PEDOT) which is one coating material. PEDOT has superior light
transmissivity when used as a thin film. A general method for
coating PEDOT uses an aqueous dispersion made of a mixture of PEDOT
and polystyrenesulfonate (PSS), i.e., PEDOT-PSS.
The organic light emitting layer 30 is, for example,
light-transmissive. The organic light emitting layer 30 is, for
example, transparent. The organic light emitting layer 30 overlaps
the substrate 40 in the Z-axis direction. The organic light
emitting layer 30 is provided between the first electrode 10 and
the second electrode 20. The organic light emitting layer 30 is
electrically connected with both the first electrode 10 and the
second electrode 20. In the specification of the application, the
state of being electrically connected includes not only the state
of being in direct contact but also the state in which another
conductive member or the like is interposed therebetween.
The thickness (the length in the Z-axis direction) of the first
electrode 10 is, for example, not less than 10 nanometers (nm) and
not more than 300 nm. The thickness of the second electrode 20 is,
for example, not less than 10 nm and not more than 500 nm. More
favorably, the thickness is not less than 50 nm and not more than
200 nm. The thickness of the organic light emitting layer 30 is,
for example, not less than 50 nm and not more than 500 nm.
From the perspective of the light extraction efficiency, it is
favorable for the refractive index of the second electrode 20 to be
higher than the refractive index of the substrate 40 and lower than
the refractive index of the organic light emitting layer 30. More
favorably, the refractive index of the second electrode 20 is 1.6
or less. For example, the refractive index of the substrate 40 is
1.5. The refractive index of the second electrode 20 is 1.6. The
refractive index of the organic light emitting layer 30 is 1.8.
A current is caused to flow in the organic light emitting layer 30
by using the second electrode 20 and the first electrode 10.
Thereby, the organic light emitting layer 30 emits light. For
example, when the current flows in the organic light emitting layer
30, electrons and holes recombine and generate excitons. For
example, the organic light emitting layer 30 emits light by
utilizing the emission of light when the excitons undergo radiative
deactivation.
FIG. 2 is a schematic cross-sectional view showing a portion of the
organic electroluminescent element according to the first
embodiment.
As shown in FIG. 2, the organic light emitting layer 30 includes a
first layer 31. The organic light emitting layer 30 may further
include at least one of a second layer 32 or a third layer 33 as
necessary. The first layer 31 emits light of a wavelength of
visible light. The second layer 32 is provided between the first
layer 31 and the second electrode 20. The third layer 33 is
provided between the first layer 31 and the first electrode 10.
The first layer 31 may include, for example, a material such as
Alq.sub.3 (tris(8-hydroxyquinolinolato)aluminum), F8BT
(poly(9,9-dioctylfluorene-co-benzothiadiazole), PPV
(polyparaphenylene vinylene), etc. The first layer 31 may include a
mixed material of a host material and a dopant added to the host
material. For example, CBP (4,4'-N,N'-bis dicarbazolyl-biphenyl),
BCP (2,9-dimethyl-4,7 diphenyl-1,10-phenanthroline), TPD
(4,4,-bis-N-3 methylphenyl-N-phenylamino biphenyl), PVK (polyvinyl
carbazole), PPT (poly(3-phenylthiophene)), etc., may be used as the
host material. For example, Flrpic (iridium (III)bis(4,6-d
i-fluorophenyl)-pyridinate-N,C2'-picolinate), Ir(ppy).sub.3
(tris(2-phenylpyridine)iridium), Flr6
(bis(2,4-difluorophenylpyridinato)-tetrakis
(1-pyrazolyl)borate-iridium (III)), etc., may be used as the dopant
material.
For example, the second layer 32 functions as a hole injection
layer. The hole injection layer includes, for example, at least one
of PEDOT-PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic
acid)), CuPc (copper phthalocyanine), MoO.sub.3 (molybdenum
trioxide), or the like. For example, the second layer 32 functions
as a hole transport layer. The hole transport layer includes, for
example, at least one of .alpha.-NPD
(4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl), TAPC
(1,1-bis[4-[N,N-di (p-tolyl)amino]phenyl]cyclohexane), m-MTDATA
(4,4',4''-tris[phenyl(nn-tolyl)amino]triphenylamine), TPD
(bis(3-methyl phenyl)-N,N'-diphenylbenzidine), TCTA
(4,4',4''-tri(N-carbazolyl)triphenylamine), or the like. For
example, the second layer 32 may have a stacked structure of the
layer that functions as the hole injection layer and the layer that
functions as the hole transport layer. The second layer 32 may
include a layer other than the layer that functions as the hole
injection layer and the layer that functions as the hole transport
layer.
The third layer 33 may include, for example, a layer that functions
as an electron injection layer. The electron injection layer
includes, for example, at least one of lithium fluoride, cesium
fluoride, lithium quinoline complex, or the like. The third layer
33 may include, for example, a layer that functions as an electron
transport layer. The electron transport layer includes, for
example, at least one of Alq.sub.3 (tris(8 quinolinolato)aluminum
(III)), BAlq (bis(2-methyl-8-quinolinolato)
(p-phenylphenolate)aluminum), Bphen (bathophenanthroline), 3TPYMB
(tris[3-(3-pyridyl)-mesityl]borane), or the like. For example, the
third layer 33 may have a stacked structure of the layer that
functions as the electron injection layer and the layer that
functions as the electron transport layer. The third layer 33 may
include a layer other than the layer that functions as the electron
injection layer and the layer that functions as the electron
transport layer.
For example, the light that is emitted from the organic light
emitting layer 30 is substantially white light. In other words, the
light that is emitted from the organic electroluminescent element
110 is white light. Here, "white light" is substantially white and
includes, for example, white light that is reddish, yellowish,
greenish, bluish, violet-tinted, etc.
As shown in FIG. 1, the first conductive unit 51 is provided
between the substrate 40 and the second electrode 20. The first
conductive unit 51 includes a side surface 51a intersecting the
Z-axis direction. In the example, the side surface 51a is tilted
with respect to the Z-axis direction. The side surface 51a is
provided in a tapered configuration.
The first conductive unit 51 functions as a supplemental
interconnect layer. The first conductive unit 51 includes, for
example, at least one element selected from the group consisting of
Mo, Ta, Nb, Al, Ni, and Ti. For example, a mixed film including
elements selected from the group may be used as the first
conductive unit 51. A stacked film including these elements may be
used as the first conductive unit 51. The first conductive unit 51
may include, for example, a stacked film of Nb/Mo/Al/Mo/N b.
For example, the first conductive unit 51 may be a thin metal
interconnect of about 100 nm. However, a certain amount of surface
area is necessary to ensure sufficient conductivity. In such a
case, the light emission surface area is sacrificed. Therefore, it
is favorable to ensure the conductivity by making the first
conductive unit 51 somewhat thick. For example, it is favorable for
the thickness of the first conductive unit 51 to be not less than
10 nm and not more than 800 nm. The second conductive unit 52 is
similar to the first conductive unit 51.
The first insulating layer 60 may include an insulative material.
The first insulating layer 60 includes, for example, a resin
material such as a polyimide resin, an acrylic resin, etc., an
inorganic material such as a silicon oxide film (e.g., SiO.sub.2),
a silicon nitride film (e.g., SiN), a silicon oxynitride film, etc.
The first insulating layer 60 is not limited to these materials. It
is favorable for the thickness of the first insulating layer 60 to
be, for example, not less than 100 nm and not more than 1
.mu.m.
In the embodiment, the second electrode 20 is provided between the
substrate 40 and the first electrode 10. The second electrode 20
includes a first electrode region (a first region) 21 and a second
electrode region (a second region) 22. The direction connecting the
first electrode and the second electrode region 22 intersects the
Z-axis direction.
The first conductive unit 51 is provided between the first
electrode region 21 and a portion of the substrate 40 and is
electrically connected with the second electrode 20. The first
conductive unit 51 includes a first conductive region (a third
region) p1 and a second conductive region (a fourth region) p2. A
portion p2a of the second conductive region p2 is disposed between
the substrate 40 and at least a portion of the first conductive
region p1.
The first insulating layer 60 includes a first insulating region (a
fifth region) 61. The first insulating region 61 is provided
between the first conductive region p1 and the second electrode
region 22 in the X-axis direction.
Specifically, one other portion p2b of the second conductive region
p2 does not overlap the first insulating region 61 in the Z-axis
direction. For example, the one other portion p2b of the second
conductive region p2 contacts the second electrode 20. In other
words, a portion of the first conductive unit 51 which is the
supplemental interconnect is exposed from the first insulating
layer 60 and electrically connects the second electrode 20 of
PEDOT, etc.
The first insulating layer 60 may further include a second
insulating region (a sixth region) 62. The second insulating region
62 is provided between the first conductive unit 51 and the first
electrode region 21 of the second electrode 20.
Here, for example, a transmission-type electroluminescent panel may
be considered as one method for utilizing the organic
electroluminescent element. In the case of the transmission-type
electroluminescent panel, compared to a conventional panel, it is
necessary to improve the characteristics such as the luminance, the
durability, etc., because the light emission surface area
decreases. To improve the characteristics, it is important not only
to develop materials and optimize the diode configuration but also
to optimize the light extraction structure.
Therefore, it may be considered to employ an anode material having
a low refractive index to increase the light extraction efficiency.
For example, a coating material such as PEDOT described above is
favorable as the low refractive index material included in the
anode material. The conductivity of PEDOT is lower than the
conductivity of an indium tin oxide (ITO) film which is a
conventional transparent anode. Therefore, it is difficult to
increase the surface area of the organic electroluminescent
element. To supplement the low conductivity and increase the
surface area, a method may be considered in which a supplemental
interconnect and an insulating layer are provided, etc. The
insulating layer is provided between the supplemental interconnect
and the cathode to prevent shorts.
However, in the case where a coating material such as PEDOT is used
as the anode, it is difficult to perform patterning of the
supplemental interconnect and the insulating layer using a wet
process such as photolithography, etc., after forming PEDOT on the
substrate by coating. In the case where PEDOT is formed by coating
after forming the supplemental interconnect and the insulating
layer on the substrate, the electrical connection (the contact) of
the supplemental interconnect cannot be obtained.
Conversely, in the embodiment, when forming the first conductive
unit 51 as the supplemental interconnect, a portion of the first
conductive unit 51 is exposed from the first insulating layer 60
and electrically connected with the second electrode 20 of PEDOT,
etc. Thereby, even in the case where PEDOT is used as the anode,
the electrical connection of the supplemental interconnect can be
obtained. In other words, a greater surface area can be realized by
the supplemental interconnect while increasing the light extraction
efficiency by using PEDOT.
In the example, the second conductive unit 52 is arranged with the
first conductive unit 51 in the X-axis direction. A light emitting
region EA is provided in the organic electroluminescent element
110. The second electrode 20 includes a third electrode region (a
seventh region) 23 and a fourth electrode region (an eighth region)
24. The direction connecting the first electrode region 21 and the
third electrode region 23 is aligned with the X-axis direction. The
direction connecting the second electrode region 22 and the fourth
electrode region 24 is aligned with the X-axis direction.
The second conductive unit 52 is provided between the third
electrode region 23 and one other portion of the substrate 40 and
is electrically connected with the second electrode 20. The second
conductive unit 52 includes a third conductive region (a ninth
region) p3 and a fourth conductive region (a tenth region) p4. A
portion p4a of the fourth conductive region p4 is disposed between
the substrate 40 and at least a portion of the third conductive
region p3.
The organic electroluminescent element 110 further includes a
second insulating layer 60a. The second insulating layer 60a
includes a third insulating region (an eleventh region) 63. The
third insulating region 63 is provided between the third conductive
region p3 and the fourth electrode region 24 in the X-axis
direction.
The third insulating region 63 and one other portion p4b of the
fourth conductive region p4 do not overlap in the Z-axis direction.
For example, the one other portion p4b of the fourth conductive
region p4 contacts the second electrode 20. In other words, a
portion of the second conductive unit 52 which is the supplemental
interconnect is exposed from the first insulating layer 60 and
electrically connected with the second electrode 20 of PEDOT, etc.
The second insulating layer 60a may further include a fourth
insulating region (a twelfth region) 64. The fourth insulating
region 64 is provided between the second conductive unit 52 and the
third electrode region 23.
The light emitting region EA is disposed between the first
conductive unit 51 and the second conductive unit 52. The first
electrode 10, the second electrode 20, the organic layer 30, and
the substrate 40 are stacked in the light emitting region EA. The
second electrode 20 contacts the substrate 40 in the light emitting
region EA. The light emitted from the organic layer 30 in the light
emitting region EA is emitted to the outside.
Thus, according to the embodiment, an organic electroluminescent
element suited to a greater surface area can be provided.
Second Embodiment
FIG. 3 is a schematic cross-sectional view showing an organic
electroluminescent element according to a second embodiment.
FIG. 4A and FIG. 4B are schematic perspective plan views showing
the organic electroluminescent element according to the second
embodiment.
FIG. 4B is an enlarged schematic view of the enlarged portion X1 of
FIG. 4A.
The second electrode 20 and the organic light emitting layer 30 of
FIG. 3 are not shown in FIG. 4A and FIG. 4B for easier viewing of
the drawings.
The organic electroluminescent element 111 of the embodiment has a
configuration in which the first conductive unit 51 includes a
conductive unit having two different materials. In other words, the
first conductive unit 51 includes the first conductive region p1
and the second conductive region p2. The light transmittance of the
second conductive region p2 is higher than the light transmittance
of the first conductive region p1. For example, the first
conductive region p1 is a metal interconnect layer. The second
conductive region p2 is a transparent conductive unit of ITO, etc.
The first conductive region p1 includes a first side surface p11
aligned with the Z-axis direction. The second conductive region p2
includes a second side surface p21 aligned with the Z-axis
direction. The second side surface p21 is separated from the first
side surface p11 in the X-axis direction. The first conductive
region p1 and a portion of the second conductive region p2 overlap
in the Z-axis direction. The first insulating layer 60 covers
around the first conductive region p1.
The first conductive region p1 includes, for example, at least one
element selected from the group consisting of Mo, Ta, Nb, Al, Ni,
and Ti. For example, a mixed film including elements selected from
the group may be used as the first conductive region p1. A stacked
film including these elements may be used as the first conductive
region p1. The first conductive region p1 may include, for example,
a stacked film of Nb/Mo/Al/Mo/Nb. For example, the first conductive
region p1 functions as an auxiliary electrode that suppresses the
potential drop of the second electrode 20.
The second conductive region p2 includes, for example, an oxide
including at least one element selected from the group consisting
of In, Sn, Zn, and Ti. The second conductive region p2 may include,
for example, indium oxide, zinc oxide, tin oxide, an indium tin
oxide (ITO) film, fluorine-doped tin oxide (FTO), gold, platinum,
silver, copper, etc. The second conductive region p2 includes a
conductive material that is transparent or semi-transparent.
The second conductive region p2 is provided on the substrate 40.
The first conductive region p1 is provided on the second conductive
region p2. The first insulating layer 60 is provided on the first
conductive region p1. For example, patterning of the first
conductive region p1, the second conductive region p2, and the
first insulating layer 60 is performed using a method such as
photolithography, etc. The upper surface and side surface of the
first conductive region p1 are covered with the first insulating
layer 60. A portion of the second conductive region p2 is disposed
outside the first insulating layer 60. For example, the second
conductive region p2 is patterned to be exposed from the first
insulating layer 60 by an amount in the range of not less than 10
.mu.m and not more than 50 .mu.m.
The second electrode 20 is provided on the first insulating layer
60. The second electrode 20 is provided on a portion of the second
conductive region p2 exposed from the first insulating layer 60. It
is favorable for a wet process such as coating, etc., to be used to
form the second electrode 20. The organic light emitting layer 30
is provided on the second electrode 20. The first electrode 10 is
provided on the organic light emitting layer 30. For example,
vacuum vapor deposition is used to form the first electrode 10. The
region where the first insulating layer 60 is not formed is the
light emitting region EA when a voltage is applied using the second
electrode 20 as the anode.
In the description recited above, a portion of the second
conductive region p2 is exposed from the first insulating layer 60.
That is, a portion of the second conductive region p2 is positioned
in the light emitting region EA. Therefore, it is favorable for a
transparent conductive material such as ITO, etc., to be used as
the second conductive region p2. Thereby, the surface area of the
light emitting region EA is not sacrificed. Thereby, the light
extraction efficiency can be increased further.
It is desirable for a second thickness D2 along the Z-axis
direction of the first conductive region p1 to be thicker than a
first thickness D1 along the Z-axis direction of the second
conductive region p2. The second thickness D2 is, for example, not
less than 10 nm and not more than 200 nm. The first thickness D1
is, for example, not less than 100 nm and not more than 800 nm. In
other words, by increasing the thickness of the first conductive
region p1, sufficient conductivity can be obtained without
increasing the surface area of the first conductive unit 51.
According to the embodiment, the surface area of the organic
electroluminescent element can be increased; and the light
extraction efficiency can be increased further.
Third Embodiment
FIG. 5 is a schematic cross-sectional view showing a portion of an
organic electroluminescent element according to a third
embodiment.
The organic electroluminescent element 112 of the embodiment has a
configuration in which the first conductive unit 51 includes a
conductive unit having two different materials. In other words, the
first conductive unit 51 includes the first conductive region p1
and the second conductive region p2. The light transmittance of the
second conductive region p2 is higher than the light transmittance
of the first conductive region p1. For example, the first
conductive region p1 is a metal interconnect layer. The second
conductive region p2 is a transparent conductive unit such as ITO,
etc. A portion p12 of the first conductive region p1 and a portion
of the second conductive region p2 overlap in the Z-axis direction.
The first insulating layer 60 covers around the first conductive
region p1. In the embodiment, the first conductive region p1 is
provided between the second conductive region p2 and the first
insulating layer 60 and between the substrate 40 and the first
insulating layer 60.
The first conductive region p1 includes the first side surface p11
that is aligned with the Z-axis direction. The second conductive
region p2 includes the second side surface p21 that is aligned with
the Z-axis direction. The second side surface p21 is separated from
the first side surface p11 in the X-axis direction. The second
conductive region p2 further includes a first portion p22 and a
second portion p23. The second portion p23 is arranged with the
first portion p22 in the X-axis direction. One other portion p13 of
the first conductive region p1 is provided between the first
portion p22 and the second portion p23 in the X-axis direction and
contacts the substrate 40.
The second conductive region p2 is provided on the substrate 40.
The first conductive region p1 is provided on the substrate 40 and
on the second conductive region p2. The first insulating layer 60
is provided on the first conductive region p1. For example,
patterning of the first conductive region p1, the second conductive
region p2, and the first insulating layer 60 is performed using a
method such as photolithography, etc. The front surface and side
surface of the first conductive region p1 are covered with the
first insulating layer 60. A portion of the second conductive
region p2 is disposed outside the first insulating layer 60. For
example, the second conductive region p2 is patterned to be exposed
from the first insulating layer 60 by an amount in the range of not
less than 10 .mu.m and not more than 50 .mu.m.
The second electrode 20 is provided on the first insulating layer
60. The second electrode 20 is provided on a portion of the second
conductive region p2 exposed from the first insulating layer 60. It
is favorable to use a wet process such as coating, etc., to form
the second electrode 20. The organic light emitting layer 30 is
provided on the second electrode 20. The first electrode 10 is
provided on the organic light emitting layer 30. For example,
vacuum vapor deposition is used to form the first electrode 10. The
region where the first insulating layer 60 is not formed is the
light emitting region when a voltage is applied using the second
electrode 20 as the anode.
In the description recited above, a portion of the second
conductive region p2 is exposed from the first insulating layer 60.
That is, a portion of the second conductive region p2 is positioned
in the light emitting region. Therefore, it is favorable for a
transparent conductive material such as ITO, etc., to be used as
the second conductive region p2. Thereby, the surface area of the
light emitting region is not sacrificed. Thereby, the light
extraction efficiency can be increased further.
Thus, according to the embodiment, the surface area of the organic
electroluminescent element can be increased; and the light
extraction efficiency can be increased further.
Fourth Embodiment
FIG. 6 is a schematic cross-sectional view showing a lighting
device according to a fourth embodiment.
The lighting device 210 according to the embodiment includes, for
example, an organic electroluminescent element 130 and a power
supply unit 201. The organic electroluminescent element 130 further
includes a first substrate 131, a second substrate 132, and a
sealing unit 133.
As shown in FIG. 6, the second electrode 20 is provided on the
first substrate 131. The first substrate 131 is light-transmissive.
The second substrate 132 opposes the first substrate 131. The
second substrate 132 is light-transmissive. In the example, the
configuration of the stacked body is the same as the configuration
described in regard to the organic electroluminescent element 111
(FIG. 3). The configuration of the stacked body may be the
configuration described in regard to another organic
electroluminescent element.
For example, the sealing unit 133 is provided in an annular
configuration along the outer edge of the first substrate 131 and
the second substrate 132 and bonds the first substrate 131 to the
second substrate 132. Thereby, the stacked body is sealed with the
first substrate 131 and the second substrate 132. In the organic
electroluminescent element 130, the distance in the Z-axis
direction between the first substrate 131 and the second substrate
132 is regulated by the sealing unit 133. For example, such a
configuration can be realized including spacers (not shown) having
granular configurations in the sealing unit 133. For example, the
multiple spacers having the granular configurations are dispersed
in the sealing unit 133; and the distance between the first
substrate 131 and the second substrate 132 is regulated by the
diameter of the multiple spacers.
In the organic electroluminescent element 130, the thickness (the
length along the Z-axis direction) of the sealing unit 133 is, for
example, not less than 1 .mu.m and not more than 100 .mu.m. More
favorably, the thickness is, for example, not less than 5 .mu.m and
not more than 20 .mu.m. Thereby, for example, the penetration of
moisture, etc., can be suppressed. The thickness of the sealing
unit 133 is, for example, substantially the same as the diameter of
the spacers dispersed in the sealing unit 133.
There is a configuration of the organic electroluminescent element
in which a recess is provided in the second substrate 132 to
contain the stacked body. For such a configuration, it becomes
difficult to form the second substrate 132. For example, this may
cause a cost increase of the organic electroluminescent
element.
Conversely, in the organic electroluminescent element 130 according
to the embodiment, the distance between the first substrate 131 and
the second substrate 132 is regulated by the sealing unit 133.
Thereby, for example, the second substrate 132 having a flat plate
configuration can be used. For example, the formation of the second
substrate 132 can be easy. The cost increase of the organic
electroluminescent element 130 can be suppressed.
For example, an inert gas, etc., is filled into the space between
the stacked body and the second substrate 132. A desiccant, etc.,
may be provided between the stacked body and the second substrate
132. For example, the space between the stacked body and the second
substrate 132 may be an air layer. For example, a liquid acrylic
resin, epoxy resin, etc., may be filled into the space between the
stacked body and the second substrate 132. Calcium oxide or barium
oxide may be added to the acrylic resin or the epoxy resin as a
desiccant.
The first substrate 131 and the second substrate 132 include, for
example, a glass substrate, a resin substrate, etc. The sealing
unit 133 includes, for example, an ultraviolet-curing resin,
etc.
The power supply unit 201 is electrically connected with the second
electrode 20 and the first electrode 10. The power supply unit 201
supplies the current to the organic light emitting layer 30 via the
second electrode 20 and the first electrode 10. According to the
embodiment, a lighting device suited to a greater surface area can
be provided.
Fifth Embodiment
FIG. 7A and FIG. 7B are schematic views showing lighting systems
according to a fifth embodiment.
As shown in FIG. 7A, a lighting system 311 according to the
embodiment includes, for example, the organic electroluminescent
elements 130 and a controller 301.
The controller 301 is electrically connected with each of the
multiple organic electroluminescent elements 130 and controls the
intensity of the light emission of each of the multiple organic
electroluminescent elements 130. For example, the controller 301 is
electrically connected with the first electrode and the second
electrode of each of the multiple organic electroluminescent
elements 130. Thereby, the controller 301 individually controls the
intensity of the light emission of each of the multiple organic
electroluminescent elements 130.
In a lighting system 312 as shown in FIG. 7B, the multiple organic
electroluminescent elements 130 are connected in series. The
controller 301 is electrically connected with the first electrode
of one organic electroluminescent element 130 of the multiple
organic electroluminescent elements 130. The controller 301 is
electrically connected with the second electrode of one other
organic electroluminescent element 130 of the multiple organic
electroluminescent elements 130. Thereby, the controller 301
controls the intensity of the light emission for each of the
multiple organic electroluminescent elements 130 collectively.
Thus, the controller 301 may control the intensity of the light
emission of each of the multiple organic electroluminescent
elements 130 individually or collectively.
According to the embodiment, a lighting system suited to a greater
surface area can be provided.
According to the embodiments, an organic electroluminescent
element, a lighting device, and a lighting system suited to a
greater surface area can be provided.
Hereinabove, embodiments of the invention are described with
reference to specific examples. However, the invention is not
limited to these specific examples. For example, one skilled in the
art may similarly practice the invention by appropriately selecting
specific configurations of components such as the substrate, the
first electrode, the second electrode, the organic layer and the
first conductive unit, etc., from known art; and such practice is
within the scope of the invention to the extent that similar
effects can be obtained.
Further, any two or more components of the specific examples may be
combined within the extent of technical feasibility and are
included in the scope of the invention to the extent that the
purport of the invention is included.
Moreover, all organic electroluminescent elements, lighting devices
and lighting systems practicable by an appropriate design
modification by one skilled in the art based on the organic
electroluminescent elements, lighting devices and lighting systems
described above as embodiments of the invention also are within the
scope of the invention to the extent that the spirit of the
invention is included.
Various other variations and modifications can be conceived by
those skilled in the art within the spirit of the invention, and it
is understood that such variations and modifications are also
encompassed within the scope of the invention.
While certain embodiments have been described, these embodiments
have been presented by way of example only, and are not intended to
limit the scope of the inventions. Indeed, the novel embodiments
described herein may be embodied in a variety of other forms;
furthermore, various omissions, substitutions and changes in the
form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
invention.
* * * * *